The invention relates to thermoplastic a matrix/compound having improved mechanical properties.
A thermoplastic is a plastic that softens when heated and hardens again when cooled. Thermoplastics can generally go through many melt/freeze cycles with no appreciable chemical change, making them suitable for recycling. These characteristics also lend thermoplastics to various manufacturing techniques, injection molding, thermoforming and welding.
Many thermoplastic materials are addition polymers (chain growth polymers), such as polyethene and polypropylene.
Thermoplastic polymers are contrasted with thermosetting polymers, which cannot go through melt/freeze cycles.
The mechanical and thermomechanical properties of a material are essential parameters for the design of manufactures articles.
In order to give a material the best possible properties, it is often sought to modify it using suitable chosen additives or fillers.
This technique is used in particular for the production of thermoplastic compounds.
The possibility of improving the impact strength of thermoplastic polymers by incorporating mineral inclusions, of a chosen size and concentration, in a matrix is also known.
It is known to use glass fibres to increase the modulus of a thermoplastic. Glass fibres are large-sized objects, which considerably weaken the materials. In addition, they must be used in high concentrations, of the order of 40%. For example, polyamides containing glass fibres have a high modulus but a low elongation at break. In addition, the materials obtained have a low fatigue strength.
To improve the modulus of thermoplastics, fillers of a much smaller size than fibres have been proposed. Patent FR 1 134 479 describes compositions based on nylon-6 containing silica particles having a particle size of 17 to 200 nm. More recently, materials have been described which contain plate-like mineral particles, for example exfoliated montmorillonites (U.S. Pat. No. 4,739,007) or synthetic fluoromicas. These materials have an increased modulus but a reduced impact strength.